<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>brock</title>
    <style>
        .father {
            width: 80%;
            height: 500px;
            background-color: pink;
        }

        .son {
            width: 200px;
            line-height: 500px;
            text-align: center;
            background-color: gray;
        }
    </style>
</head>
<body>
<div>
    <span class="father">
            <span class="son">aaa</span>
    </span>
</div>

</body>
</html>